Sunday, 29 April 2012

A team of researchers from the Laboratoire Univers et Théorie (LUTH, Observatoire de Paris/CNRS/Université Paris Diderot)(1) coordinated by Jean-Michel Alimi has performed the first-ever computer model simulation of the structuring of the entire observable universe, from the Big Bang to the present day. The simulation has made it possible to follow the evolution of 550 billion particles. This is the first of three runs which are part of an exceptional project called Deus : full universe run (2), carried out using GENCI's new supercomputer CURIE at the CEA's Très Grand Centre de Calcul (TGCC)

This simulation, along with the two additional runs expected by late May 2012, will provide outstanding support for future projects dedicated to the observation and mapping of the universe. These simulations will shed light on the nature of dark energy and its effects on cosmic structure formation, and hence on the distribution of dark matter and galaxies in the universe.

And inversely, how can the nature of dark energy be inferred from observing the distribution of matter in the universe? After several years' research, six scientists(3) of the cosmology group at LUTH have performed the first-ever computer model simulation of the structuring of the entire observable universe, from the Big Bang to the present day. What imprint does dark energy leave on cosmic structures? These are two fundamental questions that the project Deus : full universe run will seek to answer This first simulation of the standard model of the universe with a cosmological constant will be followed by two additional runs focusing on the cosmological evolution of models with dark energy (4), the mysterious component introduced to account for the accelerated expansion of the universe (5).

Simulation of the standard cosmological model has already allowed researchers to discover a number of important properties concerning the distribution of matter in the universe. These clusters currently amount to 144 millions. The researchers have found that the first galaxy cluster of this type formed when the universe was only 2 billion years old and the most massive cluster in the observable universe today weighs 15 quadrillion (or 15 thousand trillion) solar masses. As an example, they have succeeded in estimating the total number of galaxy clusters with a mass larger than a hundred thousand billion solar masses. These measurements were obtained in a simulation covering the entire evolutionary history of the universe with previously unattained precision and on a much wider range of scales, from a few millionths to the size of the entire observable universe. These fluctuations have the same origin as those found in the Cosmic Microwave Background radiation, resulting from the Big-Bang and observed by the WMAP and Planck satellites. This simulation already seems like a gold mine of new results for the cosmology community The data generated by the run has also allowed the scientists to evaluate spatial distribution of dark matter density fluctuations in the universe. This also revealed with unprecedented accuracy the imprint of the primordial plasma's acoustic oscillations on the distribution of dark matter ("Baryon Acoustic Oscillations").

The implementation of this exceptional project would not have been possible without the powerful resources made available to the researchers by the " Grand Equipement National de Calcul Intensif " (GENCI) (6), whose new supercomputer CURIE is equipped with more than 92 000 CPUs and can perform 2 million billion operations per second (2 PFlop/s). The CURIE supercomputer is housed and operated by the CEA at the " Très Grand Centre de Calcul, at Bruyères-le-Châtel (Essonne). Designed by Bull, it is one of the world's five most powerful supercomputers.

Thanks to an advanced and innovative data reduction process developed by the researchers, the amount of useful stored data can now be reduced to 1 PBytes More than 150 PBytes of data (the equivalent of 30 million DVDs) are generated throughout the computing runs. The entire project will use more than 30 million hours (about 3500 years) of computing time on virtually all CPUs of CURIE. The first simulation in the project has largely outperformed the most advanced cosmological simulations carried out over the past few years by a number of international collaborations at the largest supercomputing facilities around the world. The implementation of Deus : full universe run represents a new stage in the development of supercomputing.

In the standard cosmological model with a cosmological constant, it is now possible to go through the distribution of dark matter and galaxies across the cosmos over a distance equivalent to 90 billion light-years (7) and follow their evolution throughout the entire history of the universe.

They will also provide exceptional support for the development and interpretation of present and future cosmic catalogues from major observational projects, especially those launched by international space agencies. These include the EUCLID mission(8), which has been selected by ESA, the European Space Agency These results will improve current understanding of the influence of dark energy on the structure of the universe. The results of these voyages across the full observable universe, from the present day back to the Big Bang for the three cosmological models, are expected by late May 2012.

Notes

(1) LUTH is a laboratory of Observatoire de Paris/CNRS/Université Paris Diderot and a science department of the Paris Observatory.

(4) The first model is the concordance cosmological model characterized by the presence of a cosmological constant. The second model is characterized by a dynamical dark energy component, which fills the entire universe. Finally, the third model mimics a modification of the law of gravity at large scales by taking into account the effects of an accelerating component dubbed " phantom " dark energy.

(5) The observational discovery of the accelerated expansion of the universe of which dark energy could be the cause was awarded the 2011Nobel Prize in Physics.

(7) In a universe nearly 13.7 billion years old, light travels a distance farther than 13.7 light-years due to the effect of cosmic expansion during travel time. This distance depends on the cosmological model considered. Since the space is dilated by the expansion during travel-time, light covers nearly 45 billion light-years.

Friday, 27 April 2012

Astronomers at The University of Manchester believe they have found the answer to the mystery of a powerful 'superwind' which causes the death of stars.

Writing in Nature, the team of researchers used new techniques which allowed them to look into the atmospheres of distant, dying stars.

The team, lead by Barnaby Norris from the University of Sydney in Australia, includes scientists from the Universities of Manchester, Paris-Diderot, Oxford and Macquarie University, New South Wales. They used the Very Large Telescope in Chile, operated by the European Southern Observatory.

At the resolution used by the scientists, one could, from the UK, distinguish the two headlights on a car in Australia. This extreme resolution made it possible to resolve the red giant stars, and to see winds of gas and dust coming off the star.

This wind occurs over a period of 10,000 years, and removes as much as half the mass of the star. Stars like the Sun end their lives with a 'superwind', 100 million times stronger than the solar wind. The Sun will begin to throw out these gases in around five billion years At the end, only a dying and fading remnant of the star will be left.

The star light pushes the dust grains (silicates) away from the star The cause of this superwind has remained a mystery. Scientists have assumed that they are driven by minute dust grains, which form in the atmosphere of the star and absorb its light.

However, models have shown that this mechanism does not work well. The dust grains become too hot, and evaporate before they can be pushed out.

The scientists have now discovered that the grains grow to much larger sizes than had previously been thought. The team found sizes of almost a micrometer -- as small as dust, but huge for stellar winds.

Grains of this size behave like mirrors, and reflect starlight, rather than absorbing it. This leaves the grains cool, and the star light can push them out without destroying them. This may be the solution to the mystery of the superwind.

The large grains are driven out by the star light at speeds of 10 kilometres per second, or 20 thousand miles per hour -- the speed of a rocket. Compared to grains of sands, the silicates in the stellar winds are still tiny The effect is similar to a sandstorm.

Professor Albert Zijlstra, from The University of Manchester's Jodrell Bank Observatory, said the breakthrough changes our view of these superwinds. For the first time, we begin to understand how the superwinds work, and how stars (including, in the distant future, our Sun) die.

He added: "The dust and sand in the superwind will survive the star, and later become part of the clouds in space from which new stars form. " We are now a big step further in understanding this cycle of life and death. The sand grains at that time become the building blocks of planets. Our own Earth has formed from star dust.

Wednesday, 25 April 2012

On the Border Between Matter and Anti-Matter: Nanoscientists Find Long-Sought Majorana Particle.

Scientists at TU Delft's Kavli Institute and the Foundation for Fundamental Research on Matter (FOM Foundation) have succeeded for the first time in detecting a Majorana particle. In the 1930s, the brilliant Italian physicist Ettore Majorana deduced from quantum theory the possibility of the existence of a very special particle, a particle that is its own anti-particle: the Majorana fermion. That 'Majorana' would be right on the border between matter and anti-matter

Nanoscientist Leo Kouwenhoven already caused great excitement among scientists in February by presenting the preliminary results at a scientific congress. Today, the scientists have published their research in Science. The research was financed by the FOM Foundation and Microsoft.

Quantum computer and dark matter

Such a computer is far more powerful than the best supercomputer, but only exists in theory so far. Majorana fermions are very interesting -- not only because their discovery opens up a new and uncharted chapter of fundamental physics; they may also play a role in cosmology. Furthermore, scientists view the particles as fundamental building blocks for the quantum computer. Contrary to an 'ordinary' quantum computer, a quantum computer based on Majorana fermions is exceptionally stable and barely sensitive to external influences A proposed theory assumes that the mysterious 'dark matter', which forms the greatest part of the universe, is composed of Majorana fermions.

Nanowire

For the first time, scientists in Leo Kouwenhoven's research group managed to create a nanoscale electronic device in which a pair of Majorana fermions 'appear' at either end of a nanowire. "The measurements of the particle at the ends of the nanowire cannot otherwise be explained than through the presence of a pair of Majorana fermions," says Leo Kouwenhoven They did this by combining an extremely small nanowire, made by colleagues from Eindhoven University of Technology, with a superconducting material and a strong magnetic field.

Particle accelerators

The current Large Hadron Collider appears to be insufficiently sensitive for that purpose but, according to physicists, there is another possibility: Majorana fermions can also appear in properly designed nanostructures. " Microsoft approached Leo Kouwenhoven to help them lead a special FOM programme in search of Majorana fermions, resulting in a successful outcome We happened to be very familiar with those ingredients here at TU Delft through earlier research. It is theoretically possible to detect a Majorana fermion with a particle accelerator such as the one at CERN. "What's magical about quantum mechanics is that a Majorana particle created in this way is similar to the ones that may be observed in a particle accelerator, although that is very difficult to comprehend," explains Kouwenhoven. "In 2010, two different groups of theorists came up with a solution using nanowires, superconductors and a strong magnetic field.

Ettore Majorana

He discovered a hitherto unknown solution to the equations from which quantum scientists deduce elementary particles: the Majorana fermion. Whether he killed himself, was murdered or lived on under a different identity is still not known. But Ettore Majorana the person is every bit as mysterious as the particle. The Italian physicist Ettore Majorana was a brilliant theorist who showed great insight into physics at a young age. In 1938 he withdrew all his money and disappeared during a boat trip from Palermo to Naples. No trace of Majorana was ever found Practically all theoretic particles that are predicted by quantum theory have been found in the last decades, with just a few exceptions, including the enigmatic Majorana particle and the well-known Higgs boson.

Monday, 23 April 2012

Expanding on previous research providing proof-of-principle that human stem cells can be genetically engineered into HIV-fighting cells, a team of UCLA researchers have now demonstrated that these cells can actually attack HIV-infected cells in a living organism.

The study, published April 12 in the journal PLoS Pathogens, demonstrates for the first time that engineering stem cells to form immune cells that target HIV is effective in suppressing the virus in living tissues in an animal model, said lead investigator Scott G. Kitchen, an assistant professor of medicine in the division of hematology and oncology at the David Geffen School of Medicine at UCLA and a member of the UCLA AIDS Institute.

"We believe that this study lays the groundwork for the potential use of this type of an approach in combating HIV infection in infected individuals, in hopes of eradicating the virus from the body," he said.

They then placed the engineered stem cells into human thymus tissue that had been implanted in mice, allowing them to study the reaction in a living organism However, these T cells, while able to destroy HIV-infected cells, do not exist in great enough quantities to clear the virus from the body. So the researchers cloned the receptor and used this to genetically engineer human blood stem cells. In the previous research, the scientists took CD8 cytotoxic T lymphocytes -- the "killer" T cells that help fight infection -- from an HIV-infected individual and identified the molecule known as the T cell receptor, which guides the T cell in recognizing and killing HIV-infected cells.

The researchers also discovered that HIV-specific T cell receptors have to be matched to an individual in much the same way an organ is matched to a transplant patient The engineered stem cells developed into a large population of mature, multi-functional HIV-specific CD8 cells that could specifically target cells containing HIV proteins.

In this current study, the researchers similarly engineered human blood stem cells and found that they can form mature T cells that can attack HIV in tissues where the virus resides and replicates. They did so by using a surrogate model, the humanized mouse, in which HIV infection closely resembles the disease and its progression in humans.

In a series of tests on the mice's peripheral blood, plasma and organs conducted two weeks and six weeks after introducing the engineered cells, the researchers found that the number of CD4 "helper" T cells -- which become depleted as a result of HIV infection -- increased, while levels of HIV in the blood decreased. These results indicated that the engineered cells were capable of developing and migrating to the organs to fight infection there CD4 cells are white blood cells that are an important component of the immune system, helping to fight off infections.

So the use of multiple, engineered T cell receptors may be one way to adjust for the higher potential for HIV mutation in humans The researchers did note a potential weakness with the study: Human immune cells reconstituted at a lower level in the humanized mice than they would in humans, and as a result, the mice's immune systems were mostly, though not completely, reconstructed. Because of this, HIV may be slower to mutate in the mice than in human hosts.

"We believe that this is the first step in developing a more aggressive approach in correcting the defects in the human T cell responses that allow HIV to persist in infected people," Kitchen said.

The researchers will now begin making T cell receptors that target different parts of HIV and that could be used in more genetically matched individuals, he said.

Saturday, 21 April 2012

When this question is viewed strictly classically, the answer is clearly no, as there is no reaction mass to be used to conserve momentum. The idea of pushing off the vacuum is not new, in fact the idea of a “quantum ramjet drive” was proposed by Arthur C. The Dirac vacuum, an early vacuum model, predicted the existence of the electron’s antiparticle, the positron in 1928, which was later confirmed in the lab by Carl Anderson in 1932. However, Quantum Electrodynamics (QED), which has made predictions verified to 1 part in 10 billion, also predicts that the quantum vacuum (lowest state of the electrodynamic field) is not empty, but rather a sea of virtual particles and photons that pop into and out of existence stemming from the Heisenberg uncertainty principle. Confirmation that the Quantum Vacuum (QV) would directly impact lab observations came inadvertently in 1948 while Willis Lamb was measuring the 2s and 2p energy levels in the hydrogen atom. This force has been measured and found to agree with predictions numerous times in multiple laboratories since its derivation Can the properties of the quantum vacuum be used to propel a spacecraft? ”. Clark (proposer of geosynchronous communications satellites in 1945) in the book Songs of Distant Earth in 1985: “If vacuum fluctuations can be harnessed for propulsion by anyone besides science fiction writers, the purely engineering problems of interstellar flight would be solved. Willis discovered that the energy levels were slightly different, contrary to prediction, but detailed analysis performed within weeks of the discovery by Bethe at Cornell predicted the observed difference only when factoring in contributions from the QV field The Casimir force, derived in 1948 by Casimir in response to disagreements between experiment and model for precipitation of phosphors used with fluorescent light bulbs, predicts that there will be a force between two nearby surfaces due to fluctuations of the QV.

What is the Casimir force? The Casimir force is a QV phenomenon such that two flat plates placed in close proximity in the vacuum preclude the appearance of particles, whose wavelength is larger than the separation gap, and the resultant negative pressure between the two surfaces is more negative than the pressure outside the two surfaces, hence they experience an attractive force.

Using the Plank frequency as upper cutoff yields a prediction of ~10^114 J/m3. Current astronomical observations put the critical density at 1*10^-26 kg/m3. The vast difference between QED prediction and observation is not currently understood.

What is the dynamic Casimir force? The magnitude of thrust arising from using the dynamic Casimir force derived numerous times in the literature has been shown to be very small in comparison with conventional propulsion systems, but has been clearly shown to be theoretically possible The dynamic Casimir force arises as a result of Unruh radiation where an accelerated observer sees the vacuum as a higher temperature photon bath, and is the mechanism that facilitates Hawking radiation around a black hole where relativistic acceleration separates a virtual pair such that one particle goes in the horizon, while the other escapes. The simplest mechanical construct to help visualize using the dynamic Casimir force to generate thrust is through the use of vibrating mirrors where the mirror trajectory is designed to generate radiation in a preferred direction. Recent findings reported earlier in 2011 show that the dynamic Casimir effect may have been detected in the lab.

Recent models developed by White suggests that there are ways to increase the net force, and these models have been validated against data at both the cosmological scale, the quantum level, and test devices have been fabricated/ tested in the lab and found to agree with model predictions.

The near term focus of the laboratory work is on gathering performance data to support development of a Q-thruster engineering prototype targeting Reaction Control System (RCS) applications with force range of 0. The team is maintaining a dialogue with the ISS national labs office for an on orbit DTO Up first will be testing of a refurbished test article to duplicate historical performance on the high fidelity torsion pendulum (1-4 mN at 10-40 W). 3-3 kW. 1-1 N with corresponding input power range of 0.

In 70 days, the same system could reach the orbit of Saturn Making minimal extrapolation of performance, assessments show that delivery of a 50 mT payload to Jovian orbit can be accomplished in 35 days with a 2 MW power source [specific force of thruster (N/kW) is based on potential measured thrust performance in lab, propulsion mass (Q-thrusters) would be additional 20 mT (10 kg/kW), and associate power system would be 20 mT (10 kg/kW)]. Q-thruster performance allows the use of nuclear reactor technology that would not require MHD conversion or other more complicated schemes to accomplish single digit specific mass performance usually required for standard electric propulsion systems to the outer solar system. How would Q-thrusters revolutionize human exploration of the outer planets?

Is it possible tocreatesyntheticviruses thattake advantage of theweaknessof the host?Time will tell.Comfortingis thatresearchers believeit is unlikelythat suchtechnology will bedevelopedfor military purposes.Specifically,such aviruscould easilyinfectthe military andcivilianperson whouses it.Bioterroristis another story....

However, new measurements ofVenusExpressorbiterhavesurprisedexpertsbecause theyfound thatthesameparts ofthe planetareless than 20kilometersfrom wherethey should beaccording to previousmeasurements andcalculations. In otherwords,Venusturnson its axisin 6.5minutesslowerthan16 years ago. Similar resultsareshownandradarmeasurementsfrom Earth.

This is whyan engineerStephenSalterinventeda way to"cool"the planetandsave the lifeon it.The Faroe Islandsis planningto build atowerthatwould be "sucked"sea water, and againreturnedto the atmosphere,thuscooling.

The areacovered by icein the Arcticeachsummerisless, since thetemperatureof air andsea in thelast fewyearshave increased dramatically.The growthtemperaturehasledto the release oflarge quantities ofmethaneinto the air.Ifthe Arcticicedisappears,the amount ofmethanein the atmosphere,and on the mainland,will drasticallyincreaseand leadto an even greaterincrease intemperatureof the earth.The firststepin preventinga disasterjustbuildingtowersin the Faroe Islands,the scientistsexplain.